Wastewater treatment system

ABSTRACT

A water treatment system for treating water. The water treatment system includes a primary water treatment station and a solid-based sulfurous generator downstream from the primary water treatment station for producing aqueous sulfurous acid for further treatment of the water. In one embodiment, the solid-based sulfurous generator includes a hydraulic air inlet shut off valve safety system for automatically reducing the combustion air to the sulfurous generator when water is not delivered to the solid-based sulfurous generator. Also, in one embodiment, the water treatment system includes a control system that monitors the pH of the treated water to control the water flow rate through the solid-based sulfurous generator to achieve the desired concentration of sulfurous acid in the water being treated.

RELATED APPLICATIONS

This application claims priority to co-pending U.S. Provisional PatentApplication Ser. No. 60/452,515 filed on Mar. 6, 2003.

BACKGROUND

1. Field of the Invention

The present invention relates generally to water treatment systems and,more particularly, to a water treatment system which utilizes aqueoussulfurous acid produced by a solid sulfur-based sulfurous generator forfurther treatment of the water.

2. Description of the Prior Art

In wastewater treatment facilities, a main stream of wastewatertypically is treated with a chlorine-containing compound, such as sodiumhypochlorite, to neutralize bacteria in the wastewater stream. It isundesirable to under treat the wastewater stream because active bacteriawill thus remain in the wastewater stream. It is also undesirable toover treat the wastewater with chlorine because a residual chlorinelevel in the wastewater stream will be detrimentally high. Additionally,the chlorine or other treatment fluid is wasted and additional chemicalis typically needed to neutralize the excess chlorine.

Wastewater treatment facilities can incur fines for releasingwastewater, which is either under treated or over treated with chlorinecontaining compounds. Wastewater treatment facilities additionallysuffer financially from the unnecessary use of excess chlorine andchlorine neutralizing chemicals, such as sulfur dioxide when thechlorination/de-chlorination process is not operating optimally.

Many advanced wastewater treatment systems include a residual chlorineanalyzer downstream from the chlorinator, which monitors the levels ofchlorine residual remaining in the wastewater stream. One such system isdisclosed in U.S. Pat. No. 6,346,198, issued to Watson et al., which ishereby incorporated by reference in its entirety. Controllers mayutilize the results of this downstream analyzer to provide a feedbacksignal to the chlorinator. In essence, if an amount of residual chlorineis too high at the downstream analyzer, the chlorinator receives afeedback signal, which decreases the rate of introduction of chlorine.If the analyzer detects that no chlorine or too little chlorine remains,indicative that not all of the bacteria has been neutralized, thefeedback signal may cause the chlorinator to increase the rate withwhich it introduces chlorine.

When compressed sulfur dioxide gas is used to neutralize the excesschlorine, there is not only its cost but also the danger associated withits use. Sulfurous acid generators have been used for other watertreatment applications such as treating the irrigation water used bygolf courses and agricultural facilities. Two such generators aredescribed in U.S. Pat. No. 4,526,771, issued to Forbush et al. and U.S.Pat. No. 6,248,299, issued to Jackson. Both of these patents are herebyincorporated by reference in their entirety. However, these generatorsare not adapted for wastewater treatment nor do they typically includethe necessary safety systems that would be required.

Thus, there remains a need for a new and improved water treatment systemwhich utilizes aqueous sulfurous acid produced by a solid sulfur-basedsulfurous generator for further treatment of the water while, at thesame time, includes a shut-off safety system to prevent leakage ofmolten sulfur from the sulfurous generator.

BRIEF SUMMARY OF THE INVENTION

The present invention is directed to a water treatment system fortreating water. The water treatment system includes a primary watertreatment station and a solid-based sulfurous generator downstream fromthe primary water treatment station for producing aqueous sulfurous acidfor further treatment of the water. In one embodiment, the solid-basedsulfurous generator includes a hydraulic air-inlet shut off valve safetysystem. Also, the water treatment system may include a control systemthat monitors the pH of water being treated to control the water flowrate through the generator to achieve the desired concentration ofsulfurous acid in the water being treated.

The primary waste treatment station is generally conventional in designand includes settling tanks and holding cells for receiving the water tobe treated. The water treatment system may further include a secondarywater treatment station including aeration tanks and clarifiersdownstream from the primary water treatment station. Finally, the watertreatment system may further include a tertiary water treatment stationdownstream from the primary water treatment station.

In one embodiment, the aqueous sulfurous acid is produced by asolid-based sulfurous generator having a hydraulic air inlet shut offvalve safety system for automatically reducing the combustion air to thegenerator when water is not delivered to the generator. In oneembodiment, the solid-based sulfurous generator includes a solid sulfursupply, a burning chamber for burning the solid sulfur, an air inlet forproviding combustion air to the burning chamber, a hot SO₂ gas outlet,and a mixing and collection chamber.

The burning chamber may further include a water-cooled bottom plate forsolidifying molten sulfur in the burning chamber to form a seal. Thesealing bottom plate is removable for cleaning the burning chamber. Theburning chamber may include an igniter, such as a cal-rod inserted intothe burning chamber.

In one embodiment, a negative pressure source downstream from the hotSO₂ gas outlet draws SO₂ gas out of the burning chamber and combustionair into the burning chamber. The negative pressure source may be aventuri, an air amplifier, or a water aspirator. In one embodiment, thewater inlet port on the aspirator may be offset to maximize the“swirling” effect of the water and the negative pressure created by theaspirator. In addition to creating negative pressure to remove SO₂ gasfrom the burning chamber and to draw combustion air into the burningchamber, the introduction of water through the aspirator also serves tomix the SO₂ gas with water and convert it into sulfurous acid (H₂SO₃).

Also, in one embodiment, a scrub tower is located downstream from thehot SO₂ gas outlet for capturing any residual SO₂ gas that was notconverted into sulfurous acid by the aspirator. The scrub tower includesa high surface area reaction surface and a supply of water for reactingwith the residual SO₂ gas. In one embodiment, high surface area reactionsurface is a moisture-resistant material, such as rashing rings formedfrom plastic tubing. In one embodiment, the rashing rings have a lengthbetween about 0.5 and 1.5 inches and a diameter between about 0.5 and1.5 inches. In addition, the flow rate of the water into the scrub towermay be greater than about 80 GPM at greater than about 20 PSI tooptimize the conversion of residual SO₂ gas into sulfurous acid. This isalso referred to as optimum tail removal efficiency.

The scrub tower may further include a vapor recovery means. The vaporrecovery means includes an air inlet for providing additional air intothe scrub tower, an air mover for removing air and vapors from the scrubtower, and a percolation chamber for receiving and dissipating the airand vapors. In one embodiment, the air mover is a second wateraspirator.

In one embodiment, the control system includes a pH sensor for sensingthe pH of the water being treated. It also includes a controllerconnected to the pH sensor for receiving a signal representative of thepH, which it compares to the desired water pH. It then provides anoutput control signal to a flow control means connected to thecontroller for adjusting the water flow rate through the solid-basedsulfurous generator to achieve the desired concentration of sulfurousacid in the water being. In one embodiment, the flow control meansincludes either a conventional water valve or a variable frequency drive(VFD). The VFD may control the flow rate of water delivered by a pumpsystem by adjusting the pump speed, said pump being located between theprimary water treatment station and the solid-based sulfurous generator.As an alternative, the VFD may also adjust a valve opening to controlthe water flow rate through the valve, said valve being located betweenthe primary water treatment station and the solid-based sulfurousgenerator.

The control system may further include a feed load cell for determiningthe weight of sulfur being fed to the sulfurous generator and a timercircuit for calculating the feed burn rate based on the change in theoutput of the feed load cell over time. Also, the control system mayfurther include a flow meter for measuring the flow rate of waterthrough the solid-based sulfurous generator and a timer for selectivelystarting and stopping the solid-based sulfurous generator. In addition,the system may also include a residual chlorine analyzer, such as taughtby U.S. Pat. No. 6,346,198, issued to Watson et al. located, forexample, near the pH sensor.

Accordingly, one object of the present invention is to provide a watertreatment system for treating water, the water treatment systemincludes: a primary water treatment station; and a solid-based sulfurousgenerator downstream from the primary water treatment station forproducing aqueous sulfurous acid for further treatment of the water.

Another object of the present invention is to provide an apparatus forproducing aqueous sulfurous acid, the apparatus includes: a solid-basedsulfurous generator; and a hydraulic air inlet shut off valve safetysystem for automatically reducing the combustion air to the sulfurousgenerator when water is not delivered to the sulfurous generator.

Still another object of the present invention is to provide a watertreatment system for treating water, the water treatment systemincludes: a primary water treatment station; a solid-based sulfurousgenerator downstream from the primary water treatment station forproducing aqueous sulfurous acid for further treatment of the water, thesolid-based sulfurous generator including a hydraulic air inlet shut offvalve safety system for automatically reducing the combustion air to thesulfurous generator if water is not delivered to the sulfurousgenerator; and a control system that monitors the pH of the water beingtreated to control the water flow rate through the solid-based sulfurousgenerator to achieve the desired concentration of sulfurous acid in thewater being treated.

BRIEF DESCRIPTION OF THE DRAWINGS

The foregoing and other objects and features of the present inventionwill become more fully apparent from the following description andappended claims, taken in conjunction with the accompanying drawings.Understanding that these drawings depict only typical embodiments of theinvention and are, therefore, not to be considered limiting of itsscope, the invention will be described with additional specificity anddetail through use of the accompanying drawings in which:

FIG. 1 is a water treatment system constructed according to the presentinvention;

FIG. 2 is an front view of the solid-based sulfurous generator;

FIG. 3 is a right-side view of the solid-based sulfurous generator shownin FIG. 2;

FIG. 4 is an enlarged partial-side view of the solid-based sulfurousgenerator shown in FIG. 2, illustrating the hydraulic air inlet shut offvalve safety system;

FIG. 5 is a graphical representation of relative tail removal efficiencyof the scrub tower as a function of inner diameter and length of therashing rings;

FIG. 6 is a graphical representation of relative tail removal efficiencyof the scrub tower as a function of the water pressure and flow rate ofthe water into the scrub tower;

FIG. 7 is a function block diagram of the control system, which controlsthe production of aqueous sulfurous acid;

FIG. 8 is a side view a water aspirator; and

FIG. 9 is a top view of a water aspirator illustrating the offset waterinlet port.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

It will be readily understood that the components of the presentinvention, as generally described and illustrated in the Figures herein,could be arranged and designed in a wide variety of differentconfigurations. Thus, the following more detailed description of theembodiments of the system and method of the present invention, asrepresented in FIGS. 1 through 9, is not intended to limit the scope ofthe invention, as claimed, but is merely representative of the presentlypreferred embodiments of the invention.

In the following description, like reference characters designate likeor corresponding parts throughout the several views. Also in thefollowing description, it is to be understood that terms such as“forward,” “rearward,” “left,” “right,” “upward,” “downward,” and thelike are words of convenience and are not to be construed as limitingterms.

Referring to FIG. 1, a water treatment system is shown constructedaccording to the present invention. The water treatment system mayinclude a primary water treatment station 12, a solid-based sulfurousgenerator 14 for producing aqueous sulfurous acid, and a control system16 that monitors the pH of the water being treated. The data gathered bythe control system 16 may be used to adjust a water flow control means74 and control the water flow rate through the solid-based sulfurousgenerator 14 to achieve the desired concentration of sulfurous acid inthe water being treated.

The primary water treatment station 12 is generally conventional indesign and includes settling tanks 20 and holding cells 22. The primarysettling tank provides for removal of solids that are heavy and sink tothe bottom, as well as materials that float to the surface, such as oiland grease. The settling tank 20 holds the water being treated forseveral hours. During that time, most of the heavy solids fall to thebottom of the tank where they become a thick slurry, know as primarysludge. The material that floats is skimmed from the surface of thetanks. Both the primary sludge and skimmed materials may be pumped to asolids treatment process in a conventional manner.

Downstream from the primary water treatment station 12 may be asecondary water treatment station 24. The secondary water treatmentstation 24 may include aeration tanks 26 and clarifiers 30. Treatedwater flowing out of the primary water treatment station 12 often stillcontains some solids and dissolved materials. The secondary watertreatment station 24 may use a known process, such as activated sludge,to create an environment where microorganisms, such as bacteria, consumethe remaining organic materials in the water being treated. For example,the aeration tanks 26 may use air bubbles to provide both mixing and theoxygen needed by the microorganisms.

The microorganisms that grow in the aeration tanks 26 eventually fall tothe bottom of the tanks. In the activated sludge process, most of thesemicroorganisms are then cycled back to the aeration tanks 26 where theycontinue to grow and remove organic materials from the water beingtreated. Excess microorganisms that grow in the secondary watertreatment station 24 are removed from the activated sludge process andthe final clarifiers 30, and may be pumped to a separate solidstreatment station (not shown) for treatment and disposal.

In one embodiment, the water treatment system of the present inventionmay include a tertiary water treatment station 32. The tertiary watertreatment station may include conventional sand filters to remove smallsolid particles. In addition, the treated water may be disinfected,usually by chlorine, to kill disease causing bacteria and viruses.Compressed SO₂ gas may be used in this process to de-chlorinate thewater after the chlorine has been introduced. However, in the presentinvention, aqueous sulfurous acid is added from solid-based sulfurousgenerator 14. A solid-based system may offer advantages in safety andcost effectiveness over using compressed SO₂ gas.

As will be discussed in more detail subsequently, the production ofaqueous sulfurous acid by the solid-based sulfurous generator 14 may becontrolled by control system 16. While discussed in more detail later,one example of a control system 16 is shown in FIG. 1. The flow rate ofwater into the tertiary water treatment station 32 may be measured byflow meter 86. This information may then be used to control the flowrate of water through the solid-based sulfurous generator to create thedesired concentration of sulfurous acid in the water being treated.

In one embodiment, the control system 16 may also sense the pH of thetreated water using pH sensor 72 to provide feedback to control thewater flow rate through the generator 14. Also, in one embodiment, thecontrol system 16 may sense the excess chlorine level in the wastewaterto provide a further feedback to control the water flow rate through thesolid-based sulfurous generator 14 to achieve the desired concentrationof sulfurous acid in the water being treated. Following treatment, thewater may be discharged to an ocean, river, lake, or stream or used forirrigation purposes.

Referring to FIG. 2, there is shown a front view of the solid-basedsulfurous generator 14. In one embodiment, the solid-based sulfurousgenerator 14 may include a solid sulfur supply 34, a burning chamber 36,and an air inlet 40 for providing combustion air to the burning chamber36. Hot SO₂ gas exits the burning chamber 36 through the gas outlet 42where it is subsequently mixed and collected in mixing and collectionchamber 49.

The burning chamber 36 may include a water-cooled sealing plate 44,which forms the bottom of the burning chamber 36. The cooler temperatureof the ring causes the molten sulfur formed in the burning chamber 36 tosolidify and seal the bottom of burning chamber 36 during normaloperation. However, this “gasket-free” seal may also allows the bottomplate of the burning chamber 36 to be easily removed for cleaning andmaintenance of the burning chamber 36. In one embodiment, the solidsulfur received in the burning chamber 36 from the solid sulfur supply34 is initially ignited by an electrically powered igniter 46, such as acal-rod.

As best seen in FIG. 4, in one embodiment, the solid-based sulfurousgenerator 14 may include a hydraulic air inlet shut off valve safetysystem 47, 57, 58. The hydraulic air inlet shut off valve safety system47, 57, 58 may use water pressure, delivered by water line 58, to extenda piston in the hydraulic cylinder 57 which opens the valve 47 on theair inlet 40 allowing air to enter the burning chamber 36. When waterstops being delivered to the generator 14, the piston retracts. Gravitymay then close the valve 47 reducing the flow of air and oxygen throughthe air inlet 40. The reduced supply of oxygen causes combustion tocease in the burning chamber 36. Without this safety system 47, 57, 58,the molten sulfur may continue to burn and possibly leak from thegenerator 14 creating a safety hazard and possibly a fire.

Referring back to FIG. 2, the solid-based sulfurous generator 14preferably is operated using a negative pressure source 48 for drawingSO₂ gas out of the burning chamber 36 and combustion air into burningchamber 36 to produce the aqueous sulfurous acid mixture. The negativepressure source 48 may be downstream from the burning chamber 36,significantly reducing the likelihood of SO₂ gas escaping from theburning chamber. The negative pressure source 48 can be any or severaltypes of air movers, including venturis and air amplifiers.

In one embodiment (see FIG. 8) the negative pressure source 48 for theburning chamber 36 may be a kinetic jet-type water aspirator with anoffset water inlet port (see FIG. 9), such as a GT-300 Main Aspiratoravailable from Aqua SO₂, Inc. of Grass Valley, Calif. The aspirator 48may operate by moving water through directed jets, which creates anegative pressure upstream from the jets. In addition, since the purposeof the solid-based sulfurous generator 14 is to produce aqueoussulfurous acid, the water aspirator 48 also introduces water and mixesit with the SO₂ gas to produce sulfurous acid.

By designing the aspirator 48 with an offset water inlet port (see FIG.9), a greater “swirling” effect may be produced which increases thenegative pressure created by the aspirator 48 when compared toaspirators with non-offset or centered water inlet ports. This resultsin higher burn rates at given flow rates when compared to non-offsetaspirators of the same size. In addition, the greater “swirling” effectmixes more SO₂ gas with water leaving less residual SO₂ gas to becaptured in the scrub tower when compared to non-offset aspirators ofthe same size, which may result in fewer SO₂ emissions.

This aspirator 48, which removes SO₂ gas from the burning chamber anddraws air and oxygen into the burning chamber by creating a negativepressure source, may also be referred to as the “main aspirator” (todistinguish it from a vapor-recovery aspirator).

FIG. 3 is a right-side view of the solid-based sulfurous generator thatwas shown in FIG. 2, illustrating the scrub tower 50 and vapor recoverymeans 56. The scrub tower 50 includes a high surface area, reactivesurface material 52 and a supply of water 54 for mixing with anyresidual SO₂ that arises from the mixing and collection chamber 49. Inone embodiment, the water is supplied from a manifold 55 which alsosupplies water to the main aspirator 48, the air mover 62 and theburning chamber cooling ring 36. Adjustable gate valves 59 andconventional pressure gauges may be used to adjust the flow of waterthrough both the main aspirator 48, the air mover 62, and the scrubtower 50.

In one embodiment, the high surface area, reactive surface material 52is a moisture-resistant material such as polyethylene plastic. Thesematerials are preferably formed from a tube of plastic, which is cutinto lengths of between about ½ and 1-½ inches for a tube having adiameter between about ½ and 1-1{fraction (1/2)} inches to form“rashing” rings. In the most preferred embodiment, the rashing rings areformed from ¾ inch inner diameter PVC pipe cut into 1-¼ inch lengths.

FIG. 5 provides a graphical representation of relative “tail removalefficiency” of the scrub tower 50 as a function of inner diameter andlength of the rashing rings. (Tail removal efficiency being defined asthe efficiency of converting residual SO₂ into sulfurous acid or H2SO3.The residual SO₂ being any SO₂ gas that was not converted into H₂SO₃ bythe introduction of water through the main aspirator 48.) As may be seenin FIG. 5, the maximum efficiency for tail removal is generally in therange of a ¾ inch inner diameter and a ¾ inch length. Smaller sizedrashing rings result in too high a bulk density for the rings and maynot allow the water that is capturing the SO₂ gas to pass through therings without puddling. In addition, as the rashing rings become toolarge and too long, the bulk density becomes too low and there is notsufficient surface area to efficiently capture the residual SO₂ gas.Moreover, having approximately the same diameter and length produces arandom and torturous path through the high surface area, reactivesurface 52, which is desirable for improved efficiency.

As best seen in FIG. 6, there is shown a graphical representation ofrelative tail removal efficiency of the scrub tower 50 as a function ofthe water pressure and flow rate of the water into the scrub tower. Asmay be seen in FIG. 6, the maximum efficiency for tail removal isgenerally in the range of greater than about 20 PSI and a flow rate ofgreater than about 80 GPM. While not intended to limit the scope of thepresent invention, it is believed that this is primarily due to kineticmixing. Consequently, lower flow rates at higher pressure and higherflow rates at lower pressures may perform similarly.

Referring back to FIG. 2, the vapor recovery means 56 is attachedthrough the top of scrub tower 50. The vapor that the vapor recoverymeans is intended to recover, is primarily a mixture of water vapor anddiatomic nitrogen, which remains after the oxygen in the combustion airis combined with the burning sulfur. The mixture of water vapor anddiatomic nitrogen appears as a “white” plume, which may be cosmeticallyunappealing to some users. The vapor recovery means 56 includes an airinlet 60 and an air mover 62, possibly a second water aspirator, formoving air through the scrub tower 50 and out of the scrub tower to apercolation chamber 64 (not shown). In one embodiment, the percolationchamber 64 is a length of conventional drainpipe buried under the earth,which provides sufficient time for the diatomic nitrogen to recombineand loose its “white” appearance.

FIG. 7 displays a function block diagram of the control system 16 forthe sulfurous generator. The control system 16 may monitor the pH of thetreated water and adjust the flow rate of the generator 14 to maintainthe water pH at a preset level. The control system 16 may bemicroprocessor based and include a pH sensor 72 and a flow ratecontroller 74. The pH sensor 72 may sense the pH of the treated waterand send this information to the microprocessor. The microprocessor maycompare the sensed pH to the desired pH setting and provide an outputcontrol signal to the flow rate controller 74 indicating whether thewater pH should be higher or lower. The flow rate controller 74 may thenadjust the pump speed, which, in turn, may affect the flow of waterthrough the generator 14 and the amount of aqueous sulfurous acidproduced by the solid-based sulfurous generator 14. As an alternative toadjusting the pump speed, the flow rate controller 74 may also adjust avalve opening to control the flow of water through the generator 14 andthe amount of aqueous sulfurous acid that is produced.

In one embodiment, the flow rate controller 74 is a variable frequencydrive (hereinafter “VFD”) for controlling the water flow rate that isdelivered to the solid-based sulfurous generator 14. As an alternative,the VFD may adjust a valve opening to control the flow rate, said valvebeing located between a pump system and the solid-based sulfurousgenerator 14.

In one embodiment, the control system 16 may further include a sulfurburn rate sensor 82, such as a feed load cell, which determines theweight of sulfur that is present in the sulfur storage bin. Themicroprocessor-based control system 16 may also include a timer circuitfor calculating the feed burn rate based on the change in the output ofthe feed load cell over time. In addition, the control valve 74 mayfurther include a flow meter for measuring the flow rate of waterthrough the solid-based sulfurous generator 14. Finally, the controlsystem 16 may include a timer for selectively starting and stopping thesolid-based sulfurous generator 14.

In one embodiment, the microprocessor-based controller 16 is a singleboard microprocessor such as those available from Motorola having aMotorola 68HC12, which includes an embedded microchip processor. Thismay be a single chip solution, which includes onboard RAM, ROM and areal-time clock. Signal conditioning, relay drivers, keypad and displaydrivers may also be on one board. In addition, a wireless data interfacemay be connected to a RF 32 port on the control system 16. The wirelessdata interface may then connect to a conventional third party wirelesstransmitter for transmitting the RF 32 signal to a remote receiver, suchas a central PC (not shown). Similarly, the control system 16 may alsoinclude an infrared LED, which allows the operator to walk up with a PDAand download the data that may be stored.

In operation, the outputs of the microprocessor-based controller 16 maybe used to actuate relay drivers. For example, relays may control a flowvalve to and from the generator 14. Also, the VFD may get a low voltagesignal to change the speed of a pump connected to the generator 14. Thesame outputs may also be used to control the igniter 46 in order to turnon the cal-rod for igniting the sulfur in the burning chamber. Otheroutputs may be used to turn on a light pole as an indicator that thegenerator is functioning, is in standby, or is defective. This type ofindicator may be particularly useful at sites where it is helpful to seethe status of the system from afar so the operator could tell that thesystem is running because the green light is on, is in standby, isdefective, or low on sulfur because the yellow light is on.

In one embodiment, controller 16 may have sixteen analog inputs so thatup to sixteen different types of sensors can be monitored. Thecontroller 16 may log the data from many different sensors by takingsamples once a minute or some other time interval. The controller 16 maystore the data in memory and provide downloads through a wireless datainterface, a PDA interface, a display driver or LED, or the like.

The controller 16 may contain a battery-operated, real-time clock chipon the circuit board that stores the time and day whether the unit haspower or not-preventing a loss of data during a power failure. Varioussettings such as targeted pH, generator run times, and start and stoptimes, may be stored in a non-volatile flash memory. These parametersmay be permanently stored in memory and saved even during power loss.The numeric values for the different sensors may be displayed on theseven segment displays.

The software may perform three different functions. First, there is atimer, which may be an event sequencer that knows the time of day andcertain events at certain times. The operator interface allows the userto establish set-up functions such as the time of day, the start time,the end time, the generator run time, and the igniter configurations andbum time. Second, the controller 16 may have three different modes whichaffect the sulfurous generator. The stop mode may prevent it fromrunning, the manual mode may run it for a certain amount of time orindefinitely, and finally, the auto-mode may use the time of day todetermine when to start and stop running.

For example, auto-mode may be set to start the sulfurous generator at11:00 AM. Automode may go through a start-up sequence. It may check thetime of day, start the pump, start the igniter 46, burn the igniter 46for the specified time period (15 seconds for example), check the flowrate and adjust the pump to establish the optimal flow rate. Finally, itmay check some parameters to make sure that the temperature in theburning chamber 36 is sufficient for proper combustion. To shut down, itmay turn off the flow of water. The hydraulic air inlet valve 47 maythen close, cutting off oxygen to the burning chamber which causescombustion to cease. Automode may then re-set itself to start and stopat another pre-determined time.

The controller 16 may also control an injection system for addingnutrients, such as solution-grade gypsum, into the water. This systemmay include a tank having a solution of materials or fertilizers, whichmay be injected into the water being treated. There also may be otherbasic timer controller events (such as aeration or circulation), whichuse the time of day to start and stop some other device that aerates orcirculates the water in a holding tank or pond.

As mentioned, substances other than gypsum may be added by thecontroller 16 to the treated water discharge system depending on thechemical make-up of the discharged water. For example, ground limestone,potassium sulfate, zinc sulfate, magnesium sulfate, ammonium sulfate,calcium nitrate, UAN-32, humic acid, and iron sulfate may be addedindividually or in selected combinations to treat, remedy, limit, orcorrect various, undesirable characteristics that may be found in thewater being treated.

Certain modifications and improvements may occur to those skilled in theart upon a reading of the foregoing description. By way of example,while single sulfurous generators according to the present invention maybe used in most applications, in some applications it may beadvantageous to gang several generators together. This could beadvantageous for creating redundancy and additional capacity.

Another modification may be to utilize a large, central storage deviceto feed sulfur into a single generator or into multiple generators.Also, while the control system may further include a feed-load cell fordetermining the weight of sulfur, the mass flow of the sulfur could alsobe determined by ultrasonic or capacitance sensors. These data may thenbe used to calculate the actual volume of material inside the chamber,to estimate the bum rate and to predict when the sulfur will run out.

Finally, while in one embodiment, a control system 16 may sense the pHof the treated water and provide feedback to adjust the flow rate ofwater through the generator 14 so the pH of the water being treatedincreases, decreases or stays the same. The control system 16 may alsosense the flow rate of water into the reservoir 12 and provide feedbackto adjust the generator 14 output to reduce, increase or maintain theconcentration of sulfurous acid in the water being treated. Theseparameters may also be manually measured and adjusted. It should beunderstood that there are many modifications and improvements within thescope of the present invention.

The present invention may be embodied in other specific forms withoutdeparting from its spirit or essential characteristics. The describedembodiments are to be considered in all respects only as illustrative,and not restrictive. All changes which come within the meaning and rangeof equivalency of the claims are to be embraced within their scope.

1. A water treatment system for treating water, said water treatmentsystem comprising: a primary water treatment station; and a solid-basedsulfurous generator downstream from said primary water treatment stationfor producing aqueous sulfurous acid for further treatment of the water.2. The apparatus according to claim 1, further including a controlsystem for controlling the water flow rate through the solid-basedsulfurous generator to achieve the desired concentration of sulfurousacid in the water being treated.
 3. The apparatus according to claim 2,wherein said control system includes a pH sensor for ascertaining the pHof the water being treated; a controller connected to said pH sensor forreceiving a signal representative of the pH, comparing said signal to aset point for a desired water pH, and providing an output controlsignal, which affects a flow control means connected to said controllerfor adjusting the water flow rate through said solid-based sulfurousgenerator to achieve the desired concentration of sulfurous acid in thewater being treated.
 4. The apparatus according to claim 3, wherein saidflow control means includes a variable frequency drive for adjusting thepump speed to control the flow rate of treated water through saidsolid-based sulfurous generator, said pump being located between saidprimary water treatment station and said solid-based sulfurousgenerator.
 5. The apparatus according to claim 3, wherein said flowcontrol means includes a variable frequency drive for adjusting the flowrate through a valve to control the flow rate of treated water throughsaid solid-based sulfurous generator, said valve being located betweensaid primary water treatment station and said solid-based sulfurousgenerator.
 6. The apparatus according to claim 2, wherein said controlsystem includes a chlorine sensor for ascertaining the chlorine contentof the water being treated, a controller connected to said chlorinesensor for receiving a signal representative of the chlorine, comparingsaid signal to a set point for a desired water chlorine content, andproviding an output control signal to a flow control means connected tosaid controller for adjusting the water flow rate through saidsolid-based sulfurous generator to achieve the desired concentration ofsulfurous acid in the water being treated.
 7. The apparatus according toclaim 2, wherein said control system includes a sensor for determiningthe flow rate of water into said primary water treatment station, acontroller connected to said flow rate sensor for receiving a signalrepresentative of the flow rate and providing an output control signalto a flow control means connected to said controller for adjusting thewater flow rate through said solid-based sulfurous generator to achievethe desired concentration of sulfurous acid in the water being treated.8. The apparatus according to claim 2, wherein said control systemfurther includes feed load cell for determining the weight of sulfurbeing fed to said solid-based sulfurous generator.
 9. The apparatusaccording to claim 8, further including a timer circuit for calculatingthe feed bum rate based on the change in the output of the feed loadcell over time.
 10. The apparatus according to claim 2, wherein saidcontrol system further includes a flow meter for measuring the flow rateof water through said solid-based sulfurous generator.
 11. The apparatusaccording to claim 2, wherein said control system further includes atimer for selectively starting and stopping said solid-based sulfurousgenerator.
 12. The apparatus according to claim 1, wherein said primarywaste treatment station includes settling tanks and holding cells. 13.The apparatus according to claim 1, further including a secondary watertreatment station downstream from said primary water treatment station.14. The apparatus according to claim 13, wherein said secondary watertreatment station includes aeration tanks and clarifiers.
 15. Theapparatus according to claim 13, further including a tertiary watertreatment station downstream from said primary water treatment station.16. An apparatus for producing aqueous sulfurous acid, said apparatuscomprising: a solid-based sulfurous generator; and a hydraulic air inletshut-off valve safety system for automatically reducing the combustionair to said sulfurous generator when water is not delivered to saidsolid-based sulfurous generator.
 17. The apparatus according to claim16, wherein said solid-based sulfurous generator includes a solid sulfursupply, a burning chamber for burning said solid sulfur, an air inletfor providing combustion air to said burning chamber, and a hot SO₂ gasoutlet.
 18. The apparatus according to claim 17, wherein said burningchamber further includes a one piece, water-cooled bottom plate forsolidifying molten sulfur in said burning chamber to form a seal. 19.The apparatus according to claim 18, wherein said sealing bottom plateis removable for cleaning said burning chamber.
 20. The apparatusaccording to claim 17, wherein said burning chamber further includes anigniter.
 21. The apparatus according to claim 20, wherein said igniteris a cal-rod inserted into said burning chamber.
 22. The apparatusaccording to claim 17, further including a mixing and collection chamberconnected to said hot SO₂ gas outlet.
 23. The apparatus according toclaim 17, further including a negative pressure source downstream fromsaid hot SO₂ gas outlet for drawing the combustion air into said burningchamber.
 24. The apparatus according to claim 23, wherein said negativepressure source is a venturi.
 25. The apparatus according to claim 23,wherein said negative pressure source is an air amplifier.
 26. Theapparatus according to claim 23, wherein said negative pressure sourceis a water aspirator.
 27. The apparatus according to claim 26, whereinsaid water aspirator is a kinetic jet-type aspirator.
 28. The apparatusaccording to claim 27, wherein said kinetic jet-type aspirator has anoffset water inlet port.
 29. The apparatus according to claim 17,further including a scrub tower downstream from said hot SO₂ gas outletfor capturing the SO₂ gas.
 30. The apparatus according to claim 29,wherein said scrub tower includes a high surface area reaction surfaceand a supply of water for reacting with the SO₂ gas.
 31. The apparatusaccording to claim 30, wherein said high surface area reaction surfaceis a moisture-resistant material.
 32. The apparatus according to claim31, wherein said moisture-resistant materials are rashing rings formedfrom plastic tubing.
 33. The apparatus according to claim 32, whereinsaid rashing rings have a length between about 0.5 and 1.5 inches and adiameter between about 0.5 and 1.5 inches.
 34. The apparatus accordingto claim 30, wherein the flow rate of said water supply is greater thanabout 80 GPM at greater than about 20 PSI.
 35. The apparatus accordingto claim 29, wherein said scrub tower further includes a vapor recoverymeans.
 36. The apparatus according to claim 35, wherein said vaporrecovery means includes an air inlet for providing additional air intosaid scrub tower, an air mover for removing air and vapors from saidscrub tower, and a percolation chamber for receiving and dissipatingsaid air and vapors.
 37. The apparatus according to claim 36, whereinsaid air mover is a water aspirator.
 38. A water treatment system fortreating water, said water treatment system comprising: a primary watertreatment station; a solid-based sulfurous generator downstream fromsaid primary water treatment station for producing aqueous sulfurousacid for further treatment of the water, said solid-based sulfurousgenerator includes a hydraulic air inlet shut off valve safety systemfor automatically reducing the combustion air to said sulfurousgenerator if water stops being delivered to said sulfurous generator;and a control system for monitoring the pH of the treated water toadjust the water flow rate through said solid-based sulfurous generatorto achieve the desired concentration of sulfurous acid in the waterbeing treated.
 39. The apparatus according to claim 38, wherein saidcontrol system includes a pH sensor for sensing the pH of the waterbeing treated, a controller connected to said pH sensor for receiving asignal representative of the pH, comparing said signal to a set pointfor a desired water pH, and providing an output control signal to a flowcontrol means connected to said controller for adjusting the flow rateof water through said solid-based sulfurous generator to achieve thedesired concentration of sulfurous acid in the water being treated. 40.The apparatus according to claim 39, wherein said flow control meansincludes a variable frequency drive for controlling the speed of thepump that delivers water to said solid-based sulfurous generator, saidpump being located between said primary water treatment station and saidsolid-based sulfurous generator.
 41. The apparatus according to claim39, wherein said flow control means includes a variable frequency drivefor controlling the water flow rate through a valve, said valve beinglocated between said primary water treatment station and saidsolid-based sulfurous generator.
 42. The apparatus according to claim38, wherein said control system includes a chlorine sensor for sensingthe chlorine content of the water being treated, a controller connectedto said chlorine sensor for receiving a signal representative of thechlorine, comparing said signal to a set point for a desired waterchlorine content, and providing an output control signal to a flowcontrol means connected to said controller for adjusting the water flowrate through said solid-based sulfurous generator to achieve the desiredconcentration of sulfurous acid in the water being treated.
 43. Theapparatus according to claim 38, wherein said control system furtherincludes a feed load cell for determining the weight of sulfur beingutilized by said solid-based sulfurous generator.
 44. The apparatusaccording to claim 43, further including a timer circuit for calculatingthe bum rate based on the change in the output of the feed load cellover time.
 45. The apparatus according to claim 38, wherein said controlsystem further includes a flow meter for measuring the flow rate ofwater through said solid-based sulfurous generator.
 46. The apparatusaccording to claim 38, wherein said control system further includes atimer for selectively starting and stopping said solid-based sulfurousgenerator.
 47. The apparatus according to claim 38, wherein said primarywastewater treatment station includes settling tanks and holding cells.48. The apparatus according to claim 38, further including a secondarywater treatment station downstream from said primary water treatmentstation.
 49. The apparatus according to claim 48, wherein said secondarywater treatment station includes aeration tanks and clarifiers.
 50. Theapparatus according to claim 48, further including a tertiary watertreatment station downstream from said primary water treatment station.51. The apparatus according to claim 38, wherein said solid-basedsulfurous generator includes a solid sulfur supply, a burning chamberfor burning said solid sulfur, an air inlet for providing combustion airto said burning chamber, and a hot SO₂ gas outlet.
 52. The apparatusaccording to claim 51, wherein said burning chamber further includes aone piece, water-cooled bottom plate for solidifying molten sulfur insaid burning chamber to form a seal.
 53. The apparatus according toclaim 52, wherein said sealing bottom plate is removable for cleaningsaid burning chamber.
 54. The apparatus according to claim 51, whereinsaid burning chamber further includes an igniter.
 55. The apparatusaccording to claim 54, wherein said igniter is a cal-rod inserted intosaid burning chamber.
 56. The apparatus according to claim 51, furtherincluding a mixing and collection chamber connected to said hot SO₂ gasoutlet.
 57. The apparatus according to claim 51, further including anegative pressure source downstream from said hot SO₂ gas outlet fordrawing the SO₂ gas from said burning chamber and fresh combustion airinto said burning chamber.
 58. The apparatus according to claim 57,wherein said negative pressure source is a venturi.
 59. The apparatusaccording to claim 57, wherein said negative pressure source is an airamplifier.
 60. The apparatus according to claim 57, wherein saidnegative pressure source is a water aspirator.
 61. The apparatusaccording to claim 60, wherein said water aspirator is a kineticjet-type aspirator. 62 The apparatus according to claim 61, wherein saidkinetic jet-type aspirator includes an offset air inlet port.
 63. Theapparatus according to claim 61, further including a scrub towerdownstream from said hot SO₂ gas outlet for capturing the SO₂ gas. 64.The apparatus according to claim 63, wherein said scrub tower includes ahigh surface area reaction surface and a supply of water for reactingwith the SO₂ gas.
 65. The apparatus according to claim 64, wherein saidhigh surface area reaction surface is a moisture-resistant material. 66.The apparatus according to claim 65, wherein said moisture-resistantmaterials are rashing rings formed from plastic tubing.
 67. Theapparatus according to claim 66, wherein said rashing rings have alength between about 0.5 and 1.5 inches and a diameter between about 0.5and 1.5 inches.
 68. The apparatus according to claim 64, wherein theflow rate of said water into said scrub tower is greater than about 80GPM at greater than about 20 PSI.
 69. The apparatus according to claim63, wherein said scrub tower further includes a vapor recovery means.70. The apparatus according to claim 69, wherein said vapor recoverymeans includes an air inlet for providing additional air into said scrubtower, an air mover for removing air and vapors from said scrub tower,and a percolation chamber for receiving and dissipating said air andvapors.
 71. The apparatus according to claim 70, wherein said air moveris a water aspirator.
 72. A method for treating water in a primary watertreatment station, said method comprising the steps of: producingaqueous sulfurous acid for further treatment of the water by asolid-based sulfurous generator downstream from said primary watertreatment station; and monitoring the pH of the water being treated tocontrol the water flow rate through said solid-based sulfurous generatorto achieve the desired concentration of sulfurous acid in the waterbeing treated.